now you can introspect a program at sequence points

$ cat get-ticks 
use v6;

use Yapsi;

my $out = '';
my $clear = method ($out:) { $out = '' }
my $io-collector = class { method say($i) {$out ~= $i ~ "\n"} };

class Tardis::Debugger is Yapsi::Runtime {
    method tick {
        say 'tick';
        my %p;
        for $!env.pads.keys -> $block {
            my @variables;
            for $!env.pads{$block}.keys -> $var {
                push @variables, $var => self.get-value-of($var);
            }
            %p{$block} = @variables;
        }
        say %p.perl;
        say 'io position: ', $out.chars;
    }
}

my $program = 'my $a; $a = 42; ++$a; say $a';
Tardis::Debugger.new(:io($io-collector)).run(
    Yapsi::Compiler.new.compile($program)
);

$ alpha get-ticks 
tick
{"main" => ["\$a" => "Any()"]}
io position: 0
tick
{"main" => ["\$a" => 42]}
io position: 0
tick
{"main" => ["\$a" => 43]}
io position: 0
tick
{"main" => ["\$a" => 43]}
io position: 3